This invention relates in general to a hitch construction for articulated motor vehicles and, in particular, to an articulated motor vehicle hitch for pivotally connected draft and trailer units.
More specifically this invention relates to a hitch connection for joining draft and trailer units of an articulated motor vehicle wherein the two units are interconnected for functional control by means of cables or hydraulic lines.
Articulated motor vehicles are generally large vehicles which necessitate relative pivotal movement between the articulated units. Such vehicles are used, for example, as construction machinery equipment for transporting and discharging earth and similar materials, and utilize a so-called "fifth wheel" connection between the draft and supported trailer units. This fifth wheel connection couples the trailer to the draft or tractive unit so that it may be pulled thereby, and also provides for steering of the vehicle by turning the draft unit with respect to the trailer.
The draft or tractive unit and the supported trailer are also interconnected by cables and/or hydraulic lines so that a machine operator on the draft unit can control functions of the trailer unit through operation of controls situated within the vehicle cab to operate actuators on the trailer. Heretofore such interconnecting controls between the units have been positioned together and extended from the draft unit to the trailer unit over the vertical coupling shaft of the fifth wheel connecting between the units. The routing of such control lines in this manner presents a potential safety hazard in that the control lines are exposed during operation of the machine and may become severed or damaged during machine operation. In addition, routing of the control lines in this manner adds to the height of the machine impairing operator visability and presents an objectionable appearance.
One attempt to eliminate certain of the problems associated with the coupling of the control lines between the draft and trailer units is disclosed in P. F. McAdams, U.S. Pat. No. 3,032,135, "POWER STEERING MECHANISM". This prior art discloses a vehicle hitch for articulated vehicles wherein the vertical pivot connection or vertical hitch shaft has been replaced by two co-axially spaced pivot connections joining the draft unit to the draft frame of the trailer. While such a construction of a vehicle hitch eliminates some of the problems heretofore associated with coupling the interconnected control cables and/or hydraulic lines between the draft and trailer units, such a structure is complicated and may be susceptible to damage in the field. In addition, due to the operation of these vehicles at high speeds over uneven terrain, difficulties have been encountered in providing suitable hitch constructions that can withstand the severe stresses imposed for protracted periods.